The present disclosure relates to a device that recognizes symbols in images, and more particularly to a symbol recognition device suitable for recognition of numerals included in road speed signs. The present disclosure also relates to a traffic sign recognition device provided with a symbol recognition device.
In recent years, due to the increased number of widely used automobiles, the increase in the number of traffic accidents has become serious. Main causes of traffic accidents are responsibility of drivers such as delays in finding events, judgment errors, operation errors, etc. In order to prevent traffic accidents before they occur, judgment may be made by automobiles, to assist operations of the drivers, so that operation errors and judgment errors by the drivers can be prevented. To permit such judgment by an automobile, it is necessary to perform white road line recognition, pedestrian recognition, vehicle recognition, road sign recognition, etc. in real-time while the automobile is moving.
The road sign recognition includes detection of road speed signs and recognition of numerals. Conventionally, images are subjected to thinning processing and then pattern matching to recognize symbols such as letters, numerals, and marks (see FRANK Y. SHIH, “IMAGE PROCESSING AND PATTERN RECOGNITION—Fundamentals and Techniques—,” John Wiley & Sons, Inc., 2010, pp. 233-253, for example).
The image thinning processing is a technique for software, which requires repetitively accessing an image from an image memory. Therefore, it is difficult to apply this technique in hardware implementation such as an automotive embedded system to perform real-time processing while the automobile is moving.